1. Field of the Invention
The present invention generally relates to tubular endoluminal prostheses, such as stents, stent-grafts, and the like. More particularly, the present invention provides improved delivery systems and methods for their use to accurately and safely deploy endoluminal prostheses within the lumens of the body, particularly within the vascular system for treatment of aortic aneurysms, stenoses, and the like.
Vascular aneurysms are the result of abnormal dilation of a blood vessel, usually resulting from disease and/or genetic predisposition, which can weaken the arterial wall and allow it to expand. While aneurysms can occur in any blood vessel, most occur in the aorta and peripheral arteries, with the majority of aortic aneurysms occurring in the abdominal aorta, usually beginning below the renal arteries and often extending into one or both of the iliac arteries.
Aortic aneurysms are now commonly treated in open surgical procedures where the diseased vessel segment is bypassed and repaired with an artificial vascular graft. While considered to be an effective surgical technique, particularly considering the alternative of a usual fatal ruptured abdominal aortic aneurysm, conventional vascular graft surgery suffers from a number of disadvantages. The surgical procedure is complex and requires experienced surgeons and well-equipped surgical facilities. Even with the best surgeons and equipment, however, patients being treated frequently are elderly and weakened from cardiovascular and other diseases, reducing the number of eligible patients. Even for eligible patients prior to rupture, conventional aneurysm repair has a relatively high mortality rate, usually from 2% to 10%. Morbidity related to the conventional surgery includes myocardial infarction, renal failure, impotence, paralysis, and other conditions. Additionally, even with successful surgery, recovery takes several weeks, and often requires a lengthy hospital stay.
In order to overcome some or all of these drawbacks, endovascular prosthesis placement for the treatment of aneurysms has been proposed. Although very promising, many of the proposed methods and apparatus suffer from undesirable limitations. In particular, accurate delivery and placement of the endovascular prosthesis within the vasculature can be problematic.
Stent-grafts are often resilient structures, biased to expand against the surrounding lumenal wall. Such resiliently-expanding stent-grafts are tightly compressed within the catheter, imposing significant forces against the surrounding catheter sheath. This can often lead to excess friction between the stent-graft and the sheath, particularly when the resiliently-expanding structure invaginates into the catheter material. As these catheters are often required to maneuver within the tortuous vascular system, catheter sheaths are often formed as flexible, elongate bodies which are particularly susceptible to invagination of the tightly compressed stent-graft in the flexible material of the catheter wall.
For these reasons, it would be desirable to provide improved devices, systems, and methods for endoluminal deployment of prostheses such as stents, stentgrafts, and the like, for treatment of aneurysms and other diseases of the body lumens. It would be particularly desirable if such improved systems and methods enhanced the accuracy and safety of the deployment procedure, without significantly increasing deployment time, equipment costs, or complexity of the deployment procedure.
2. Description of the Background Art
Devices for endoluminal placement of prostheses are described in U.S. Pat. Nos. 4,512,338, 4,651,738, 4,665,918, 5,458,615, 5,480,423, 5,484,418, 5,489,295, 4,990,151, 5,035,706, 5,433,723, 5.443,477, 5,282,824, 5,275,622, 5,242,399, 5,201,757, 5,190,058, 5,104,399, 5,092,877, 4,990,151, and EP Patent Publication Nos. EP 0 539 237 A1, 0518839 A2, EP 0505686 A1, and EP 0508473 A2.